The present invention relates to an electronic watermark embedding apparatus to embed watermark data in image data, an image data format conversion device having an electronic watermark embedding function, and a method of embedding an electronic watermark, and in particular, to an image data processing apparatus having a function to execute an electronic watermark embedding operation in combination with a moving picture coding experts group (MPEG) 2 image format conversion.
A technique to embed particular data in various data such as video or image data, audio or voice data, and text data is called, for example, “steganography”, “watermark technique”, or “electronic watermark technique”. Heretofore, in the field of this technique, study and research have been conducted to embed related identifier information or a comment in the image data, audio data, and/or text data.
The technique has been recently applied to a field in which data to protect a copyright of such information is embedded in original data to be protected so as to thereby prevent illegal operations, for example, illegal production of copies of the data. Such techniques are described in, for example, U.S. Pat. No. 5,748,763 issued to Rhoads on May 5, 1998 and entitled “Image Steganography System Featuring Perceptually Adaptive and Globally Scalable Signal Embedding”.
When the original data is processed, for example, filtered and/or compressed and quality of the data is deteriorated, the data embedded in the original data cannot function to prevent the illegal operations. To overcome this difficulty, the data embedding method is devised so that the embedded data is still valid even after the original data is processed as above.
The original data is restricted in various levels according to the copyright. For example, the data can be freely copied, the copy of the data is prohibited, or the data can be copied only once. In such a situation, it is also possible to embed, in the original data, data associated with the restriction level. The copy operation is controlled by detecting the embedded data.